In a disc brake in which lug pieces which are provided at both end portions of support or back plates of friction pads so as to project therefrom are movably supported by pad guide portions which are formed on a pair of caliper support arms so as to face each other, so that the friction pads are allowed to move in the direction of a disc axis, in general, pad retainers, which are formed of a sheet metal, are interposed individually between the pad guide portions of the pair of caliper support arms and the lug pieces of the friction pads. As such a pad guide portion, there is a pad guide portion which is formed into a stair step-like configuration by including a torque bearing face which faces a torque bearing face of an opposite pad guide portion which makes a pair therewith and a lug piece movably supporting face which project from a disc inner circumferential side or radially inner side of the torque bearing face at a right angle thereto. As a pad retainer which is to be disposed in the pad guide portions configured in the way described above, there is a pad retainer which includes a pair of retainer portions which are disposed on the torque bearing faces, a pair of pad spring-back portions which are disposed on the lug piece movably supporting faces and a connecting piece which connects the pair of retainer portions together, and a pad spring is disposed at a radially outer side to prevent the floating of the friction pad (see JP-A-2006-336784, for instance).
Additionally, as a pad guide portion, there is a pad guide portion which is formed into a U-shape in section by including a deeper side face which faces a deeper side face of an opposite pad guide portion which makes a pair therewith, a lug piece movably supporting face which projects from a disc inner circumferential or radially inner side of the deeper side face at a right angle thereto and a disc radial direction outer face which project from a disc outer circumferential or radially outer side of the deeper side face at a right angle thereto. Then, as a pad retainer which is disposed in the pad guide portions, there is a pad retainer which includes outer pieces which are disposed on the radially outer faces and pad spring-back pieces which project from the outer pieces along the lug piece movably supporting faces so as to press the lug pieces radially outwards within the pad guide portions (see JP-A-2006-46597, for instance).
In the above-described vehicle disc brakes, the pad spring-back pieces press the lug pieces of the friction pads in the directions of the radially outer faces of the pad guide portions and the pad springs. Therefore, there is no fear that the lug pieces are caused to rattle within the pad guide portions by vibrations like those which are generated when the vehicle runs normally. However, when a larger vibration than a vibration which is generated when the vehicle runs normally is imparted to the vehicle from the outside thereof as when the vehicle runs over a bump in the road, the lug pieces is caused to vibrate due to minute gaps between the lug piece movably supporting faces of the pad guide portions and the pad spring-back pieces of the pad retainers, whereby the lug pieces collide with the pad guide portions via the pad retainers, generating striking noise from time to time.